Transmission control method and transmission control system

ABSTRACT

A transmission control method includes: determining transmission performance in a transmission line by using a parameter that determines a size of an opening of an eye pattern; and adjusting a transmission parameter that is a parameter having an influence on transmission quality in the transmission line on the basis of a result of the determination.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to a transmission control method and atransmission control system.

2. Description of the Related Art

In the related art, for example, in a storage system, it is known thatquality of transmission signal between devices deteriorates due tobreakage of a cable or deterioration thereof with the passage of time.In addition, it is also known that failure caused by the cable occurs.Here, as a technology for coping with such a situation, JP 2017-129969 Adiscloses a technology of performing route diagnosis without affectingsystem operation.

JP 2017-129969 A discloses a storage system that includes twocontrollers, four IO modules, and two storage devices, and performs aprocess of reading-out or writing of data, and the like with respect toa storage device corresponding a volume in correspondence with an inputor output request (for example, a read command or a write command) madewith respect to the volume from a host device that is a higher-leveldevice. In addition, the controllers have a diagnostic function ofdiagnosing a data transmission route (diagnosis target route) throughwhich data transmission and data reception to and from the IO modulesare performed, and determine that a status corresponds to which onestatus among three kinds of “a normal status”, “a status in whichpreventive replacement is required”, and “a status in which replacementis required” by a combination of collected equalizer variables.

However, in high-speed transmission connecting devices (for example,high-speed transmission related to PCIe), even when using the technologydisclosed in JP 2017-129969 A, it is difficult to appropriately monitorthe sign of occurrence of a failure during system operation, and as aresult, it is considered that transmission quality except when thefailure occurs is not secured, and performance or redundancy of thesystem may deteriorate as a whole.

SUMMARY OF THE INVENTION

Here, an object of the invention is to provide a transmission controlmethod and a transmission control system which are capable ofappropriately monitoring and coping with the sign of occurrence of afailure, and are capable of suppressing deterioration of performance orredundancy of a system as a whole.

According to a first aspect of the invention, there is provided thefollowing transmission control method. That is, the transmission controlmethod includes: determining transmission performance in a transmissionline by using a parameter that determines a size of an opening of an eyepattern; and adjusting a transmission parameter that is a parameterhaving an influence on transmission quality in the transmission line onthe basis of a result of the determination.

According to a second aspect of the invention, the followingtransmission control system is provided. That is, the transmissioncontrol system includes a storage unit and a first controller. The firstcontroller is connected to a first transmission line that connects ahost as a higher-level device and the storage unit. The first controllerexecutes an adjustment processing program, determines transmissionperformance in the first transmission line by using a parameter thatdetermines a size of an opening of an eye pattern, and adjusts atransmission parameter that is a parameter having an influence ontransmission quality in the first transmission line on the basis of aresult of the determination.

According to the aspect of the invention, there are provided atransmission control method and a transmission control system which arecapable of appropriately monitoring and coping with the sign ofoccurrence of a failure, and are capable of suppressing deterioration ofperformance or redundancy of a system as a whole.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a system block diagram for describing a storage system of thisembodiment;

FIG. 2 is a flowchart for describing a process of an adjustmentprocessing program;

FIG. 3 is an example of data (a threshold table, and a measured valuetable) used in this embodiment;

FIG. 4 is an example of data (period table) used in this embodiment;

FIG. 5 is a flowchart for describing a process of an autonomous controlprocessing program; and

FIG. 6 is a view for describing a relationship between a program anddata, and hardware in a storage system of this embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A configuration of a storage system of this embodiment will be describedwith reference to FIG. 1. A storage system 1 (transmission controlsystem) includes a first controller 11 (an electronic calculator), asecond controller 12, a first IO device 21, a second IO device 22, and astorage unit. The storage unit can be constructed by an appropriatestorage device (for example, a hard disk drive), and is constructed bytwo storage devices (a first storage device 31 and a second storagedevice 32) in this embodiment.

The first controller 11 includes a CPU and a switch (SW), and isprovided in a transmission line (a first transmission line) connecting ahost 41 that is a higher-level device and the first storage device 31.The first IO device 21 includes an LSI (constructed by a chip set inthis embodiment) and a ROM, and is provided between the first controller11 and the host 41.

A reception unit that is used to input data to the first controller 11and a transmission unit that is used to output data from the LSI of thefirst IO device 21 are connected to each other on the transmission line(the first transmission line). In addition, a transmission unit that isused to output data from the first controller 11 and a reception unitthat is used to input data to the LSI of the first IO device 21 areconnected to each other on the transmission line (the first transmissionline). Note that, in this embodiment, connection between the firstcontroller 11 and the first IO device 21 is set as connection based onPCIe.

The SW of the first controller 11 is configured to stop data input tothe first controller 11 and data output from the first controller 11 incorrespondence with a situation, and is provided to be controlled by theCPU of the first controller 11. In a case where data input and output toand from the first controller 11 are stopped, data transmission on thetransmission line (the first transmission line) is stopped.

The second controller 12 has a similar configuration as in the firstcontroller 11. That is, the second controller 12 includes a CPU and aswitch (SW). In addition, the second controller 12 is provided on atransmission line (a second transmission line) connecting the host 41and the second storage device 32. The second IO device 22 includes anLSI (constructed by a chip set) and a ROM as in the first IO device 21,and is provided between the second controller 12 and the host 41.Connection between the second controller 12 and the second IO device 22is set as connection based on the PCIe.

The SW of the second controller 12 is configured to stop data input tothe second controller 12 and data output from the second controller 12in correspondence with a situation, and is provided to be controlled bythe CPU of the second controller 12. In a case where data input andoutput to and from the second controller 12 are stopped, datatransmission on the transmission line (the second transmission line) isstopped.

In this embodiment, the first controller 11 and the second controller 12are capable of communicating with each other. In addition, in thestorage system 1, a service processor 51 configured to perform systemmonitoring is connected to the storage system 1. Note that, the serviceprocessor 51 is connected to the first controller 11 in FIG. 1, but theservice processor 51 may be connected to a controller different from thefirst controller 11, or may be connected to a plurality of controllers.

In the storage system 1 of this embodiment, as an example, a status of atransmission line between a controller and an IO device is monitored,and control corresponding to the status is executed. Next, the controlwill be described in detail with reference to FIG. 2. FIG. 2 is aflowchart for describing a process of an adjustment processing program.

The controller measures an eye pattern of the transmission line betweenthe controller and the IO device, and acquires an internal eye value(S101). For example, the first controller 11 executes an adjustmentprocessing program 61 to measure an eye pattern of the transmission linebetween the first controller 11 and the first IO device 21 and toacquire an internal eye value of the transmission line. On the otherhand, the second controller 12 executes the adjustment processingprogram 61 to measure an eye pattern of the transmission line betweenthe second controller 12 and the second IO device 22 and to acquire aninternal eye value of the transmission line. Note that, timing ofacquiring the internal eye value (in other words, timing of performing aprocess in S101) can be appropriately determined, and in thisembodiment, the timing is determined by execution of an autonomouscontrol processing program 62 to be described later, and the internaleye value is acquired.

Here, the above-described internal eye value will be described indetail. The internal eye value is a parameter that determines the sizeof an opening of the eye pattern. The internal eye value mayappropriately evaluate the size of the opening of the eye pattern, and acalculation method thereof is not particularly limited. In thisembodiment, the internal eye value is calculated on the basis of dataprepared in advance and data that is actually measured and acquired.

That is, as shown in FIG. 3, data (in FIG. 3, a threshold table 71) thatdetermines an opening of a satisfactory eye pattern is prepared. Forexample, this data can be set as data based on a vendor specification(that is, preferred specifications in a vendor that provides a serviceor the like). In addition, data acquired from an actually measured eyepattern (in FIG. 3, a measured value table 72), and prepared data arecompared with each other, and the internal eye value is calculated as apercentage (%) on the basis of the viewpoint as to whether or not it issimilar to an eye pattern determined by the prepared data.

Here, in this embodiment, as the value of the percentage (%) is smaller(that is, as the internal eye value is smaller), this indicates that anopening of the measured eye pattern is similar to an opening of the eyepattern determined by the prepared data (that is, indicates that theopening of the eye pattern is opened in a satisfactory manner). Incontrast, as the value of the percentage (%) is larger (that is, as theinternal eye value is larger), this indicates that the opening of themeasured eye pattern is not similar to the opening of the eye patterndetermined by the prepared data (that is, indicates that the opening ofthe eye pattern is not opened in a satisfactory manner).

As shown in FIG. 3, in this embodiment, in the threshold table 71 thatis prepared data, data (in FIG. 3, as an example, data of a length ineach of top, bottom, right, and left with a representative centralposition of the opening set as a reference) that determines the size ofthe opening of the eye pattern is provided for every kind of a signal.In addition, even in the measured value table 72, data that determinesthe opening of the eye pattern is provided for every kind of the signalso as to correspond to the threshold table 71. Accordingly, in thisembodiment, the internal eye value can be acquired for every kind of thesignal.

As an example, the internal eye value may be calculated on the basis ofa height of the opening (that is, a vertical length of the opening), anda width of the opening (that is, a horizontal length of the opening),and according to this, a reasonable internal eye value is calculated.However, the internal eye value may be calculated by a method differentfrom the calculation method (for example, by using only the height ofthe opening). In addition, comparison with the prepared data may beomitted, and the internal eye value may be directly calculated frommeasured data.

The controller determines whether or not the internal eye value is 30%or greater (S102). In a case where the internal eye value is not 30% orgreater, the process of the adjustment processing program 61 isterminated. On the other hand, in a case where the internal eye value is30% or greater, a process in S103 is executed.

That is, the controller determines whether or not the internal eye valuecorresponding to the processing condition in S102 is smaller than 50%(S103). Here, in a case where it is determined that the internal eyevalue is smaller than 50%, a process in S104 is executed. On the otherhand, in a case where the internal eye value is 50% or greater, aprocess in S111 is executed.

In the process in S103, in a case where it is determined that theinternal eye value is smaller than 50%, the controller adjusts atransmission parameter so that the internal eye value becomes smallerthan 30%. Here, the transmission parameter is a parameter having aninfluence on transmission quality in the transmission line.

When adjusting the transmission parameter, first, the controller gives anotification to another controller (S104). For example, in a case wherethe first controller 11 acquires the internal eye value equal to orgreater than 30% and less than 50%, a notification is given to thesecond controller 12. Note that, in the following description, acontroller that receives the notification in the process in S104 may bereferred to as a notification receiving controller.

The controller receives data from the controller (notification receivingcontroller) to which the notification is given in the process in S104,and confirms an operation status of the notification receivingcontroller (S105). That is, the controller confirms whether or nottransmission between the host 41 and the storage unit (in thisembodiment, the second storage device 32) is established in thetransmission line on the notification receiving controller side withoutperforming adjustment of the transmission parameter by the notificationreceiving controller.

Note that, in the process in S104 and the process in S105, directcommunication between the controllers may be performed, andcommunication through the service processor 51 may be performed. Inaddition, in a case where it could be confirmed that the transmissionbetween the host 41 and the storage unit is established withoutperforming adjustment of the transmission parameter, a process in S106is executed. On the other hand, in a case where the establishment is notconfirmed, the process in S104 is executed again.

The controller stops data input and output (S106). That is, the CPU ofthe controller stops data input and output by controlling the SW, andstops data transmission in the transmission line. For example, in a casewhere the first controller 11 stops data input and output, datatransmission in the first transmission line is stopped.

After stopping data input and output in the process in S106, thecontroller adjusts the internal eye value (S107). That is, thecontroller adjusts the transmission parameter so that the internal eyevalue determined as 30% or greater in the process in S102 becomes lessthan 30%. Here, the controller may adjust, for example, a parameter foradjusting a high-frequency component or a low-frequency component of asignal as the transmission parameter to adjust the internal eye value.In addition, the controller may adjust a parameter for adjusting asignal intensity as the transmission parameter to adjust the internaleye value.

After the internal eye value is adjusted in the process in S107, thecontroller confirms whether or not the adjusted internal eye valuebecomes less than 30% (S108). In a case where it cannot be confirmedthat the internal eye value is less than 30%, the controller executesadjustment of the internal eye value again.

After confirming that the internal eye value is adjusted to less than30%, the controller gives a notification to another controller (S109).In addition, the controller controls the SW to initiate data input andoutput so that data transmission in the transmission line can beperformed (S110). Note that, after the process in S110, the followingprocess in S119 is executed.

Next, description will be given of a process in a case where it isdetermined that the internal eye value is 50% or greater in the processin S103. In this case, the controller notifies a microprocessor (havinga configuration corresponding to the service processor 51) of a failurestatus (S111). That is, the microprocessor is notified of a failuredetermination. In addition, the controller confirms whether or not theinternal eye value on a reception unit side is 50% or greater (S112).For example, in a case where the internal eye value is 50% or greater ina transmission line that connects a transmission unit of the controllerand a reception unit of an IO device, the controller confirms whether ornot the internal eye value on the reception unit side of the IO deviceis 50% or greater. Note that, a user is notified of a result in theconfirmation process in S112 by an appropriate method. For example, theconfirmation result is output to an external device through the serviceprocessor 51, and the user is notified of the confirmation result.

In addition, package replacement of a reception unit of the controlleror a transmission unit of the controller (that is, replacement in apackage unit related to a target configuration) is performed by the userwho has acquired the confirmation result. For example, in a case wherethe user has grasped that the internal eye value on the reception unitside is not 50% or greater from the confirmation result, the userperforms package replacement of the transmission unit (S113). Forexample, in a case where the user has grasped that the internal eyevalue on the reception unit side is not 50% or greater in thetransmission line that connects the transmission unit of the controllerand the reception unit of the IO device, the user performs packagereplacement of the transmission unit of the controller. On the otherhand, in a case where the user has grasped that the internal eye valueon the reception unit side is 50% or greater from the confirmationresult, the user performs package replacement of the reception unit(S114).

In addition, in a case where the transmission unit has been replaced inthe process in S113, the internal eye value on the transmission unitside is confirmed (S115). In addition, in a case where the internal eyevalue is 30% or greater, the user is notified of the gist (S117), andthe transmission unit is replaced again by the user. On the other hand,in a case where the internal eye value is less than 30%, a process inS119 is executed.

In a case where the reception unit has been replaced in the process inS114, the internal eye value on the reception unit side is confirmed(S116). In addition, in a case where the internal eye value is 30% orgreater, the user is notified of the gist (S118), and the reception unitis replaced again by the user. On the other hand, in a case where theinternal eye value is less than 30%, a process in S119 is executed.

In the process in S119, increment in the number of times of setting,that is, the number of times of setting the internal eye value of 30% orgreater to normal (that is, setting of the internal eye value to lessthan 30%) is executed, and a result thereof is stored in a period table73 to be described below. Next, the process in S119 will also bedescribed while describing the period table with reference to FIG. 4.

The period table 73 stores data for every kind of the controller and thesignal as in the threshold table 71 and the measured value table 72, andthe period table 73 stores a period T and the number of times of settingi for every kind of the signal. Here, the period T is a period in whichthe internal eye value when a corresponding signal is transmitted isacquired through execution of the adjustment processing program 61. Notethat, the period T may be appropriately set by the user, but in thisembodiment, the period T is changed on the basis of the number of timesof setting i through execution of the autonomous control processingprogram 62 to be described later.

With regard to the number of times of setting i in the period table 73,a value incremented in the process in S119 through execution of theadjustment processing program 61 is stored. Accordingly, in a state inwhich any process in S110, S117, and S118 is not executed by theadjustment processing program 61, a value of “0” is stored. In addition,in this state, in a case where any one process is executed, increment isexecuted in the process in S119, and a value of “1” is stored.

In this embodiment, timing at which the process of the adjustmentprocessing program 61 is executed (in other words, initiation timing ofS101) is determined by execution of the autonomous control processingprogram 62. In addition, due to execution of the autonomous controlprocessing program 62, a process of acquiring and monitoring theinternal eye value during system operation (that is, an autonomouscontrol process) is performed, and automatic adjustment of thetransmission parameter, a failure determination, and the like areexecuted in correspondence with a situation. Next, the process of theautonomous control processing program 62 will be described withreference to FIG. 5. FIG. 5 is a flowchart for describing the process ofthe autonomous control processing program.

The controller executes the autonomous control processing program 62,and confirms a period of a device (that is, the period T of each signalin the period table 73) (S201). In addition, the controller confirms thenumber of times of setting i of each signal which is stored in theperiod table 73 (S202). In addition, in a case where the number of timesof setting i is “0” (S203), the adjustment processing program 61 isexecuted in the period T corresponding to the number of times of settingi in the period table 73, and the internal eye value is acquired (S204).

On the other hand, in a case where the number of times of setting i isnot “0” (S203), a determination is made as to whether the number oftimes of setting i is 1 to 6 (S205), and in a case where the number oftimes of setting i is 1 to 6, the adjustment processing program 61 isexecuted in the period T corresponding to the number of times of settingi in the period table 73 and the internal eye value is acquired (S206).In addition to this, processes (S207 to S209) related to change of theperiod T is performed. In addition, in a case where the number of timesof setting i is not 1 to 6 (that is, the number of times of setting i is7), the adjustment processing program 61 is not executed, and a processof setting the number of times of setting i to “0” (S210) and a processof changing the period T (S211) are executed.

Here, the process of the autonomous control processing program 62 in thecase of the period table 73 shown in FIG. 4 will be described in detail.

In the period table 73, since the number of times of setting i ofPCIE_RX (0, 2, 4, 6) is “0”, the controller (in FIG. 4, a controller onthe IC1 side) acquires the internal eye value in the transmission linein the case of transmitting the signals at a period T (here, 30 minutes)corresponding to the signals, and makes a determination as to whether ornot the internal eye value is less than 30%. Here, in a case where theinternal eye value is smaller than 30%, the number of times of setting ion the period table 73 is not changed, and the process is performedagain after 30 minutes.

On the other hand, in a case where the internal eye value is 30% orgreater, and the processes in S110, S117, and S119 have been performed,the number of times of setting i on the period table 73 is incremented(that is, the number of times of setting i of PCIE_RX (0, 2, 4, 6)becomes “1”). In the subsequent process (that is, after 30 minutes),since the number of times of setting i of PCIE_RX (0, 2, 4, 6) is “1”,the internal eye value is acquired and determined in S206. Here, in acase where the internal eye value is smaller than 30%, the number oftimes of setting i of PCIE_RX (0, 2, 4, 6) is not changed as “1”, but ina case where the internal eye value is 30% or greater and increment hasbeen performed in the process in S119, the number of times of setting iof PCIE_RX (0, 2, 4, 6) becomes “2”.

In addition, the controller (in FIG. 4, the controller on the IC1 side)calculates the product of the period T and the number of times ofsetting i (S207), and determines whether or not a value of the productof the period T and the number of times of setting i and a value of aninteger t match each other (S208). Here, the integer t is a parameterthat is set in advance, and a value of the integer t can be selectedfrom values of T, 2T, 3T, 4T, 5T, and 6T which are magnifications of theperiod T.

In a case where the number of times of setting i of PCIE_RX (0, 2, 4, 6)is “1”, in the process in S207, t=T×1 is calculated, and the controller(in FIG. 4, the controller on the IC1 side) determines whether or notthe calculated value matches the set integer t in the process in S208.On the other hand, in a case where the number of times of setting i ofPCIE_RX (0, 2, 4, 6) is “2”, t=T×2 is calculated in the process in S207,and the controller determines whether the calculated value matches theset integer t in the process in S208. In addition, in a case where thecalculated value matches the set integer t, change of the period T isnot performed. On the other hand, in a case where the calculated valuedoes not match the set integer t, setting is performed so that theperiod T is lengthened. In the example in FIG. 4, a process oflengthening the period T by 30 minutes is performed in S209, and theperiod T of PCIE_RX (0, 2, 4, 6) on the period table 73 is changed (thatis, in this example, the period T becomes 60).

Note that, in a case where the number of times of setting i is seventimes (that is, the condition in S205 is not satisfied), a reset processof the number of times of setting and the period (initializationprocess) is performed. That is, the number of times of setting i thatbecomes seven times in the period table 73 becomes “0” (S210), and thecorresponding period T is changed to 30 (S211).

As illustrated in FIG. 6 (view for describing a relationship between aprogram and data, and hardware), the above-described adjustmentprocessing program 61 may be appropriately executed by the CPU of thefirst controller 11 and the CPU of the second controller 12, and can bestored in an appropriate recording medium. This is also true of theautonomous control processing program 62. For example, a recordingmedium (for example, a ROM) may be provided in each of the firstcontroller 11 and the second controller 12, and the program may bestored in each recording medium. Alternatively, a recording medium (forexample, an externally attached HDD) may be provided at the outside ofthe first controller 11 or the second controller 12, and the program maybe stored in the recording medium. Note that, in FIG. 6, each of thecontrollers is described as CTL1/2.

The threshold table 71, the measured value table 72, and the periodtable 73 may be appropriately used in the program processes describedabove, and may be stored in an appropriate recording medium. Forexample, a recording medium (for example, a ROM) may be provided in eachdevice, and data related to the tables may be stored in the recordingmedium. Alternatively, the recording medium may be provided in aspecific device (for example, the ROM may be provided in thecontroller), and data related to the tables may be stored in therecording medium. In addition, the recording medium may be provided inthe service processor 51, and the tables may be stored in the recordingmedium.

In the above description, description has been given of a process (theprocess related to the adjustment processing program 61) of acquiringand adjusting the internal eye value in the transmission line betweenthe controller and the IO device, but a similar process may be performedin a transmission line between the controller and the storage unit. Inaddition, even in this case, the process by the autonomous controlprocessing program 62 may be performed.

In the above description, description has been given of a process usinga reference value (a first reference value) of the internal eye value of30% and a reference value (a second reference value) of the internal eyevalue of 50%. However, the magnitude of the reference value of theinternal eye value may be appropriately changed as long as anappropriate determination can be made as to whether a transmissionstatus is appropriate, whether adjustment of the transmission parameteris to be performed, or replacement of the reception unit or thetransmission unit is to be performed. Here, the first reference value isa reference value of the internal eye value for making a determinationas to whether or not the internal eye value is normal, and is areference value used in the above-described process in S102 in thisembodiment. The second reference value is a reference value of theinternal eye value for making a determination as to whether theautomatic adjustment process of the internal eye value is to beperformed, or whether it is regarded as a device failure and a user orthe like is notified of the gist, and is a reference value that is usedin the above-described process in S103 in this embodiment. In addition,whether or not to include the reference values (for example, setting tothe reference values or less, or less than the reference values) may beappropriately set as long as a threshold determination using thereference values of the internal eye value is performed.

The eye pattern can be measured by using an appropriate method. Forexample, a measurement device may be provided on the transmission line,and the eye pattern may be measured by using the measurement device.

In this embodiment, the storage unit is constructed by two storagedevices (the first storage device 31 and the second storage device 32),but may be constructed by three or more storage devices or one storagedevice. In this case (in a case where the storage unit is constructed byone storage device), each transmission line is connected to the commonstorage device. In addition, in this embodiment, description has beengiven of two transmission lines, but three or more transmission linesmay be provided. In addition, the controller and the IO device areprovided in each of the transmission lines, and the transmission linesare connected to individual storage devices or a common storage deviceas an example.

In the related art, in high-speed transmission between devices (forexample, high-speed transmission as in PCIe), it is difficult to performappropriate sign monitoring during system operation, and it is difficultto perform appropriate adjustment of the transmission parameter duringsystem operation. According to this, it is considered that there is roomfor an improvement from the viewpoint of deterioration of performance orredundancy of a system as a whole. In contrast, according to thetechnology of this embodiment, it is possible to perform appropriatesign monitoring (that is, the sign of occurrence of a failure ordetection of the failure) during system operation by using the internaleye value, and in addition to this, since the transmission parameter isappropriately adjusted in correspondence with a situation during systemoperation, there is an advantage that maintenance of transmissionquality can be realized, and deterioration of performance or redundancyduring system operation can be suppressed.

In addition, in a case where a difference (that is, a difference instandard correspondence between devices mounted on a substrate) ispresent in device standards, only a standard transmission parameterhaving no difference between the devices (for example, a value relatedto emphasis or equalizer) can be set (adjusted). Accordingly, in therelated art, in a device which does not cope with change of the emphasisor equalizer, or for which the change is not recommended, it isconsidered that appropriate sign monitoring may not be performed and thetransmission parameter may not be appropriately adjusted in some cases.In contrast, according to this embodiment, it is possible to performappropriate sign monitoring and it is possible to appropriately adjustthe transmission parameter by using the internal eye value.

Hereinbefore, the embodiment has been described, but the invention isnot limited to the above-described embodiment, and includes variousmodifications. For example, addition, deletion, or substitution ofanother configuration can be made with respect to a part of theconfiguration of the embodiment.

As an example of the processor, the CPU is considered, but anothersemiconductor device (for example, GPU) may be employed as long as theother semiconductor device is a main body that executes predeterminedprocesses.

What is claimed is:
 1. A transmission control method, comprising:determining transmission performance in a transmission line by using aparameter that determines a size of an opening of an eye pattern; andadjusting a transmission parameter that is a parameter having aninfluence on transmission quality in the transmission line on the basisof a result of the determination.
 2. The transmission control methodaccording to claim 1, wherein the parameter that determines the size ofthe opening of the eye pattern is determined on the basis of a height ofthe opening and a width of the opening.
 3. The transmission controlmethod according to claim 1, wherein the determination is determinationbased on a first reference value and a second reference value in whichthe size of the opening of the eye pattern is determined, and in a casewhere the second reference value is a reference value that determines asize of an opening smaller than a size of an opening determined by thefirst reference value, the transmission parameter is adjusted in a casewhere it is determined that the size of the opening of the eye patternis smaller than the first reference value or equal to or less than thefirst reference value, and the size of the opening of the eye pattern islarger than the second reference value or equal to or greater than thesecond reference value through the determination.
 4. The transmissioncontrol method according to claim 3, wherein in a case where it isdetermined that the size of the opening of the eye pattern is smallerthan the second reference value or equal to or less than the secondreference value, adjustment of the transmission parameter is notperformed, and a user is notified of the determination.
 5. Thetransmission control method according to claim 1, wherein thedetermination is executed in a period.
 6. The transmission controlmethod according to claim 5, wherein the period is changed to belengthened in correspondence with the number of times of adjustment ofthe transmission parameter.
 7. A program causing an electroniccalculator to execute the transmission control method according toclaim
 1. 8. A transmission control system, comprising: a storage unit;and a first controller connected to a first transmission line thatconnects a host as a higher-level device, and the storage unit, whereinthe first controller, executes an adjustment processing program,determines transmission performance in the first transmission line byusing a parameter that determines a size of an opening of an eyepattern, and adjusts a transmission parameter that is a parameter havingan influence on transmission quality in the first transmission line onthe basis of a result of the determination.
 9. The transmission controlsystem according to claim 8, further comprising: a second controllerconnected to a second transmission line that connects the host and thestorage unit, wherein the first controller and the second controller arecapable of communicating with each other, the second controller,executes an adjustment processing program, determines transmissionperformance in the second transmission line by using a parameter thatdetermines the size of the opening of the eye pattern, and is capable ofadjusting the transmission parameter that is a parameter having aninfluence on transmission quality in the second transmission line on thebasis of a result of the determination, and the first controller,executes the adjustment processing program, stops data transmission inthe first transmission line after confirming that the second controllerdoes not adjust the transmission parameter, and resumes the datatransmission in the first transmission line after adjusting thetransmission parameter.
 10. The transmission control system according toclaim 8, wherein the first controller, executes the adjustmentprocessing program, and performs determination based on a firstreference value and a second reference value in which the size of theopening of the eye pattern is determined, and in a case where the secondreference value is a reference value that determines a size of anopening smaller than a size of an opening determined by the firstreference value, the transmission parameter is adjusted in a case whereit is determined that the size of the opening of the eye pattern issmaller than the first reference value or equal to or less than thefirst reference value, and the size of the opening of the eye pattern islarger than the second reference value or equal to or greater than thesecond reference value.
 11. The transmission control system according toclaim 10, wherein the first controller is connected to a serviceprocessor, and is capable of communicating with the service processor,the first controller executes the adjustment processing program, and ina case where it is determined that the size of the opening of the eyepattern is smaller than the second reference value or equal to or lessthan the second reference value, the first controller notifies theservice processor of the determination without performing adjustment ofthe transmission parameter.
 12. The transmission control systemaccording to claim 8, wherein the first controller, executes anautonomous control processing program, and performs the determination inaccordance with execution of the adjustment processing program in aperiod.
 13. The transmission control system according to claim 12,wherein the first controller, executes the autonomous control processingprogram, and changes the period to be lengthened in correspondence withthe number of times of adjustment of the transmission parameter.